Polyester-based resin composition, adhesive composition, adhesive, adhesive sheet and double-sided adhesive sheet

Abstract

To provide a polyester-based resin composition which uses a raw material derived from a plant friendly to the global environment, has good adhesive physical properties to various adherends, and is excellent in adhesive physical properties such as an adhesive force and a holding force.SOLUTION: A resin composition contains a polyester-based resin (A), in which the polyester-based resin (A) contains a structural unit derived from at least one compound (a1) of dimer acids and dimer diol, and a structural unit derived from an aromatic compound (a2), the structural unit derived from the aromatic compound (a2) contains an aromatic compound derived from a thermoplastic polyester resin (excluding polyester-based resin (A)), and a number average molecular weight of the polyester-based resin (A) is 3,000 or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyester-based resin composition, and a pressure-sensitive adhesive composition, pressure-sensitive adhesive, pressure-sensitive adhesive sheet, and double-sided pressure-sensitive adhesive sheet containing the same; more specifically, the present invention relates to a polyester-based resin composition that uses environmentally friendly plant-derived raw materials and that, when made into a pressure-sensitive adhesive, has excellent adhesive properties such as adhesive strength and holding power; and a pressure-sensitive adhesive composition, pressure-sensitive adhesive, pressure-sensitive adhesive sheet, and double-sided pressure-sensitive adhesive sheet containing the same. [Background technology]

[0002] In recent years, pressure-sensitive adhesives have come to be used for joining parts, etc., in order to make products smaller and lighter. As such pressure-sensitive adhesives, pressure-sensitive adhesives using polyester-based resins, which have excellent adhesive strength, are also being considered as an alternative to the commonly used acrylic-based resins.

[0003] Meanwhile, in recent years, as part of measures to combat the depletion of fossil fuel resources and global warming, the use of plant-derived raw materials, which are renewable resources, has been recommended, and there is a demand for adhesives with a high biomass content that use plant-derived raw materials that are environmentally friendly.

[0004] As an example of a polyester-based pressure-sensitive adhesive using such plant-derived raw materials, Patent Document 1 proposes a pressure-sensitive adhesive containing a polyester resin obtained by polymerizing 90 to 50 mol % of an aromatic dicarboxylic acid and 10 to 50 mol % of a dimer acid as the dicarboxylic acid component, and 30 mol % or more of a glycol having an alkyl group in the side chain and having 4 or more carbon atoms, as the glycol component, and having excellent heat resistance and durability. Furthermore, Patent Document 2 proposes that a pressure-sensitive adhesive containing a polyester obtained by polymerizing a dimer acid as a dicarboxylic acid component and a dimer diol as a diol component, in which the diol component contains 1.04 to 2.10 moles of hydroxyl groups per mole of carboxyl groups in the dicarboxylic acid component, and a tackifier, requires a small amount of organic solvent, can be applied thickly, and has excellent adhesion, retention, and repulsion resistance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 4-328186 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-169419 Summary of the Invention [Problem to be solved by the invention]

[0006] However, although the technology disclosed in Patent Document 1 uses a plant-derived dimer acid, it still uses a petroleum-derived aromatic dicarboxylic acid in large amounts, and therefore the problem of high environmental impact remains. Furthermore, although the technology disclosed in the above Patent Document 2 reduces the environmental impact by mainly using plant-derived raw materials, the resin is too soft, so the elastic modulus when made into a pressure-sensitive adhesive sheet is too low, and therefore the adhesive properties such as adhesive strength when made into a double-sided pressure-sensitive adhesive tape tend to be inferior, and are still not satisfactory. Although the adhesive properties including adhesive strength can be improved by adding a tackifier, etc., the problem is that the degree of freedom in design is reduced because the number of essential components increases.

[0007] Generally, when a polyester resin composition is used as an adhesive, a crosslinking agent such as an isocyanate compound, an epoxy compound, or a metal chelate compound, or an additive such as a tackifier is often used. However, when a polyester resin composition is prepared using environmentally friendly plant-derived raw materials, such as long-alkyl-chain dimer acids or dimer diols, the polarity of the resulting composition tends to be very low, resulting in poor compatibility with the additives. Therefore, when the additives are used in a polyester resin composition using the long-alkyl-chain dimer acids or dimer diols, the compatibility is low, resulting in poor adhesive properties.

[0008] Therefore, under these circumstances, the present invention aims to provide a polyester-based resin composition that uses environmentally friendly recycled materials, such as plant-derived raw materials and recycled polyethylene terephthalate (PET), which, when used as an adhesive, has good adhesive properties for various adherends and excellent adhesive properties such as adhesive strength and holding power, as well as an adhesive composition, adhesive agent, adhesive sheet, and double-sided adhesive sheet containing the same. [Means for solving the problem]

[0009] However, the present inventors have discovered that in a polyester-based resin composition, the polyvalent carboxylic acids and polyols constituting the polyester-based resin include at least one compound selected from dimer acids and dimer diols, and an aromatic compound, the structural units derived from the aromatic compound include an aromatic compound derived from a thermoplastic polyester resin, and the polyester-based resin has a number average molecular weight of 3000 or more, so that when made into an adhesive, an adhesive can be obtained that is environmentally friendly, has good adhesive properties on various adherends, and is excellent in adhesive strength and holding power, and have completed the present invention.

[0010] That is, a first aspect of the present invention is a resin composition containing a polyester resin (A), wherein the polyester resin (A) contains structural units derived from at least one compound (a1) selected from dimer acids and dimer diols, and structural units derived from an aromatic compound (a2), wherein the structural units derived from the aromatic compound (a2) include an aromatic compound derived from a thermoplastic polyester resin, and the number average molecular weight of the polyester resin (A) is 3,000 or more.

[0011] In addition, in the present invention, a second aspect is a pressure-sensitive adhesive composition containing the polyester resin composition, a third aspect is a pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition, a fourth aspect is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive, and a fifth aspect is a double-sided pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive. [Effects of the Invention]

[0012] The polyester-based resin composition of the present invention contains a polyester-based resin (A), the polyester-based resin (A) containing structural units derived from at least one compound (a1) selected from dimer acids and dimer diols, and structural units derived from an aromatic compound (a2), the structural units derived from the aromatic compound (a2) including an aromatic compound derived from a thermoplastic polyester resin, and the polyester-based resin (A) having a number average molecular weight of 3,000 or more. Therefore, the polyester resin composition has a high biomass content and a high recycled carbon usage rate, and is environmentally friendly, while also exhibiting excellent adhesive strength and holding power when used as an adhesive. Therefore, it can be effectively used as a single-sided or double-sided pressure-sensitive adhesive sheet for laminating optical components, or as a single-sided or double-sided pressure-sensitive adhesive sheet for fixing components of portable electronic devices or electronic components. DETAILED DESCRIPTION OF THE INVENTION

[0013] The configuration of the present invention will be described in detail below, but these are merely examples of preferred embodiments. In the present invention, the term "carboxylic acids" includes not only carboxylic acids but also carboxylic acid derivatives such as carboxylic acid salts, carboxylic acid anhydrides, carboxylic acid halides, and carboxylic acid esters.

[0014] The polyester resin composition of the present invention contains structural units derived from at least one compound (a1) selected from dimer acids and dimer diols, and structural units derived from an aromatic compound (a2), wherein the structural units derived from the aromatic compound (a2) include an aromatic compound derived from a thermoplastic polyester resin, and the polyester resin (A) has a number average molecular weight of at least 3000. The polyester resin (A) will be described in detail below.

[0015] <Polyester resin (A)> The polyester resin has a resin structure that includes structural units derived from polycarboxylic acids and structural units derived from polyols, and is usually obtained by polymerizing polymerization components that include polycarboxylic acids and polyols.

[0016] The polyester resin (A) used in the present invention contains structural units derived from at least one compound (a1) selected from dimer acids, which are polycarboxylic acids, and dimer diol, which is a polyol, and structural units derived from at least one aromatic compound (a2) selected from polycarboxylic acids and polyols, and is obtained by polymerizing polymerization components containing at least one compound (a1) selected from dimer acids and dimer diols, and the aromatic compound (a2).

[0017] [At least one compound (a1) of dimer acids and dimer diols] The at least one compound (a1) of the dimer acids and dimer diols (hereinafter sometimes referred to as "compound (a1)") is, as described above, at least one of dimer acids, which are polycarboxylic acids, and dimer diols, which are polyols.

[0018] The dimer acids are primarily composed of unsaturated fatty acid dimers having an average carbon number of 10 to 26, preferably unsaturated fatty acid dimers having an average carbon number of 12 to 24, and more preferably unsaturated fatty acid dimers having an average carbon number of 14 to 22. Specific examples of dimer acids include dicarboxylic acids derived from unsaturated fatty acids such as oleic acids, linoleic acids, linolenic acids, and erucic acids. Here, the term "main component" refers to a component whose content is 90% by weight or more, preferably 95% by weight or more, and more preferably 98% by weight or more of the total.

[0019] Examples of the dimer acids used in the present invention include dimer acids derived from the above-mentioned unsaturated fatty acids (mainly having 36 or 44 carbon atoms), hydrogenated products of the above-mentioned dimer acids, etc. Among these, hydrogenated products of dimer acids are preferred because they are easy to prevent crystallization.

[0020] As the raw material for the dimer acid, plants, beef tallow, etc. are usually used, and in the present invention, dimer acids derived from any raw material can be used, but it is preferable to use a plant-derived raw material that is environmentally friendly. By using a plant-derived raw material, the biomass content of the polyester resin (A) described below can be increased.

[0021] When the dimer acids are used as copolymerization components of the polyester resin (A), the content of the dimer acids is preferably 10 to 100 mol % relative to the total polycarboxylic acids, particularly preferably 20 to 99 mol %, further preferably 35 to 90 mol %, and particularly preferably 51 to 80 mol %. If the content is too low, the resin tends to be too hard and the adhesive strength tends to decrease. On the other hand, if the content is too high, the resin tends to be too soft and the adhesive properties tend to decrease slightly.

[0022] The dimer diol used in the present invention is generally a diol derived from the above-mentioned dimer acids. In the present invention, the above-mentioned dimer diol is preferably a plant-derived raw material, like the dimer acids.

[0023] When the dimer diol is used as a copolymerization component of the polyester resin (A), the content of the dimer diol is preferably 10 to 100 mol % relative to the total polyol, particularly preferably 20 to 99 mol %, further preferably 35 to 90 mol %, and particularly preferably 51 to 80 mol %. If the content is too low, the adhesive properties tend to deteriorate. On the other hand, if the content is too high, the adhesive properties tend to deteriorate slightly due to excessive softening.

[0024] [Aromatic compound (a2)] The aromatic compound (a2) includes an aromatic compound derived from a thermoplastic polyester resin (excluding the polyester resin (A)). Examples of the aromatic compound derived from the thermoplastic polyester resin include aromatic polycarboxylic acids and aromatic polyols. Among these, it is preferable to use a thermoplastic polyester resin containing a structural unit derived from an aromatic polycarboxylic acid because of its excellent adhesive strength and holding power.

[0025] As the thermoplastic polyester resin, polyethylene terephthalate is preferably used. The polyethylene terephthalate is a polyester resin obtained by polymerizing terephthalic acids, which are aromatic compounds (a2), with ethylene glycol, and may be further modified with substances such as isophthalic acids, phthalic anhydrides, adipic acids, cyclohexanedicarboxylic acids, sebacic acids, 1,3-butanediol, 1,4-butanediol, and cyclohexanedimethanol, as necessary. The polyethylene terephthalate may be either virgin or recycled, but the use of recycled products is preferred from the standpoint of the global environment.

[0026] The content of the aromatic compound derived from the thermoplastic polyester resin in the copolymerization component of the polyester resin (A) is preferably 1 mol % or more and less than 50 mol %, more preferably 5 to 47 mol %, even more preferably 10 to 43 mol %, particularly preferably 15 to 40 mol %, and even more preferably 20 to 36 mol % relative to the total polycarboxylic acids. If the content is too low, the cohesive strength decreases, which tends to reduce the adhesive strength and make it impossible to obtain sufficient adhesive performance, while if the content is too high, the initial adhesive strength (tack) tends to decrease.

[0027] From the viewpoint of the global environment, it is preferable that the aromatic compound (a2) consists solely of aromatic compounds derived from thermoplastic polyesters, but it may also contain aromatic polycarboxylic acids and aromatic polyols other than aromatic compounds derived from thermoplastic polyesters.

[0028] (aromatic polycarboxylic acids) Examples of the aromatic polycarboxylic acids include divalent aromatic dicarboxylic acids and trivalent or higher aromatic polycarboxylic acids, and aromatic dicarboxylic acids are preferably used since they allow the polyester resin (A) to be stably obtained.

[0029] Examples of the aromatic dicarboxylic acids include phthalic acids, terephthalic acids, isophthalic acids, benzylmalonic acids, diphenic acids, 4,4'-oxydibenzoic acids, 1,8-naphthalenedicarboxylic acids, 2,3-naphthalenedicarboxylic acids, 2,7-naphthalenedicarboxylic acids, and other naphthalenedicarboxylic acids; and heterocyclic dicarboxylic acids such as furandicarboxylic acids and thiophenedicarboxylic acids (pyrrole, pyrazole, imidazole, pyridine, pyridazine, pyrimidine, pyrazine, etc.). These may be used alone or in combination of two or more. Among these, terephthalic acids, isophthalic acids, and furandicarboxylic acids are preferred due to their availability.

[0030] Examples of the trivalent or higher aromatic polycarboxylic acids include trimellitic acids, pyromellitic acids, trimesic acids, etc. These may be used alone or in combination of two or more.

[0031] When the aromatic polycarboxylic acids are contained as copolymerization components of the polyester resin (A), the content of these aromatic polycarboxylic acids is preferably 1 mol % or more and less than 50 mol %, more preferably 5 to 47 mol %, even more preferably 10 to 43 mol %, particularly preferably 15 to 40 mol %, and even more preferably 20 to 36 mol % of the total polycarboxylic acids. If the content is too low, the cohesive strength decreases, which tends to reduce adhesive strength and make it impossible to obtain sufficient adhesive performance, while if the content is too high, the initial adhesive strength (tack) tends to decrease.

[0032] (aromatic polyol) The aromatic polyol includes a dihydric aromatic diol. Examples of the divalent aromatic diol include bisphenol A, 4,4'-thiodiphenol, 4,4'-methylenediphenol, 4,4'-dihydroxybiphenyl, o-, m-, and p-dihydroxybenzene, 2,5-naphthalenediol, p-xylenediol, and ethylene oxide adducts and propylene oxide adducts thereof, which may be used alone or in combination of two or more.

[0033] When the aromatic polyol is contained as a copolymerization component of the polyester resin (A), the content of the aromatic polyol is preferably 1 to 50 mol %, more preferably 5 to 40 mol %, and even more preferably 10 to 30 mol %, based on the total polyol content. If the content is too low, the cohesive strength and adhesive strength tend to decrease, while if the content is too high, the initial adhesive strength tends to decrease.

[0034] The polyester resin (A) used in the present invention may contain an aliphatic compound (a3) ​​as a copolymerization component in addition to the above compound (a1) and aromatic compound (a2).

[0035] [Aliphatic compound (a3)] Examples of the aliphatic compound include aliphatic polycarboxylic acids and aliphatic polyols.

[0036] (Aliphatic polycarboxylic acids) Examples of the aliphatic polycarboxylic acids include divalent aliphatic dicarboxylic acids and trivalent or higher polycarboxylic acids. Examples of the aliphatic dicarboxylic acids include linear alkyl dicarboxylic acids such as malonic acids, dimethylmalonic acids, succinic acids, glutaric acids, adipic acids, trimethyladipic acids, pimelic acids, 2,2-dimethylglutaric acids, azelaic acids, sebacic acids, 1,9-nonanedicarboxylic acids, and decanedicarboxylic acids; and acyclic aliphatic dicarboxylic acids such as fumaric acids, maleic acids, itaconic acids, thiodipropionic acids, and diglycolic acids. Examples thereof include alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acids, 1,2-cyclohexanedicarboxylic acids, 1,3-cyclohexanedicarboxylic acids, 1,4-cyclohexanedicarboxylic acids, 2,5-norbornanedicarboxylic acids, and adamantanedicarboxylic acids. Examples of the trivalent or higher polyvalent carboxylic acids include adamantanetricarboxylic acids. These aliphatic polycarboxylic acids may be used alone or in combination of two or more.

[0037] From the viewpoint of improving initial adhesive strength (tack), the aliphatic polycarboxylic acids preferably contain acyclic aliphatic dicarboxylic acids having 4 or more carbon atoms (including the carbon atoms in the carboxy group), and more preferably contain acyclic aliphatic dicarboxylic acids having 9 to 12 carbon atoms (including the carbon atoms in the carboxy group), such as azelaic acids and sebacic acids.

[0038] The content of such acyclic aliphatic dicarboxylic acids having 4 or more carbon atoms is preferably 95 mol % or less, more preferably 5 to 90 mol %, and particularly preferably 10 to 70 mol %, based on the total amount of polycarboxylic acids. If the content is too high, the adhesive strength tends to decrease, or the resin tends to crystallize, making it difficult to obtain sufficient adhesive performance.

[0039] In addition, it is preferable to use a plant-derived aliphatic polycarboxylic acid as the aliphatic polycarboxylic acid in order to increase the biomass content. Examples of the plant-derived aliphatic polycarboxylic acids include sebacic acids derived from castor oil and succinic acids derived from corn.

[0040] (Aliphatic polyol) Examples of the aliphatic polyol include dihydric aliphatic diols and trihydric or higher aliphatic polyhydric alcohols. Examples of the divalent aliphatic diol include acyclic aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, and 2,2,4-trimethyl-1,6-hexanediol; Examples thereof include cycloaliphatic diols such as 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, spiroglycol, tricyclodecane dimethanol, adamantanediol, isosorbide, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol. Examples of the trihydric or higher aliphatic polyhydric alcohols include pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, 1,2,4-butanetriol, 1,2,5-pentanetriol, 1,3,6-hexanetriol, and adamantanetriol. These aliphatic polyols may be used alone or in combination of two or more.

[0041] Among these, it is preferable to incorporate an acyclic aliphatic diol into the polyol in order to lower the glass transition temperature (Tg) of the polyester resin (A) and improve initial adhesive strength, more preferably an acyclic aliphatic diol having 2 to 20 carbon atoms, and particularly preferably ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, or 1,6-hexanediol. Of these, ethylene glycol is particularly preferable in that it can lower the glass transition temperature (Tg) of the polyester resin (A) and improve adhesiveness.

[0042] The content of the acyclic aliphatic diol is preferably 10 to 100 mol % relative to the total polyol, more preferably 20 to 99 mol %, even more preferably 30 to 95 mol %, and particularly preferably 40 to 90 mol %. If the content is too low, it tends to be difficult to obtain stable resin formation.

[0043] The aliphatic polyol is preferably a plant-derived polyol in order to increase the biomass content. Examples of the plant-derived polyol include isosorbide, fatty acid ester diols derived from castor oil, bioethylene glycol, bio-1,3-propane glycol, biobutylene glycol, etc. Among these, bioethylene glycol is preferred.

[0044] Furthermore, polyethylene terephthalate may be used as the acyclic aliphatic diol. As mentioned above, polyethylene terephthalate is a polyester resin obtained by polymerizing terephthalic acids and ethylene glycol. Therefore, by using polyethylene terephthalate, the polyester resin (A) contains a structure consisting of ethylene glycol derived from polyethylene terephthalate as a structural unit derived from the acyclic aliphatic diol. Furthermore, the polyethylene terephthalate may be a virgin product or a recycled product, but the use of a recycled product is preferred from the viewpoint of the global environment.

[0045] Furthermore, in order to form reaction sites in the polyester resin (A) with the polyisocyanate compound (B) described below and increase cohesive strength, it is preferable to use a trivalent or higher aliphatic polyol as the aliphatic polyol, such as trimethylolpropane, trimethylolethane, glycerin, pentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, or 1,2,6-hexanetriol. Of these, trimethylolpropane is particularly preferable because it is relatively less likely to form gels.

[0046] The content of the trihydric or higher aliphatic polyhydric alcohol is preferably 20 mol % or less, more preferably 0.1 to 10 mol %, and particularly preferably 0.5 to 5 mol %, based on the total polyol content. If the content of the trihydric or higher aliphatic polyhydric alcohol is too high, production of the polyester resin (A) tends to become difficult.

[0047] As mentioned above, it is preferable to use a plant-derived aliphatic polyol. However, when the biomass degree of polyvalent carboxylic acids is high, a non-plant-derived aliphatic polyol may be used in terms of ease of polycondensation. However, even in this case, in order to increase the biomass degree, it is preferable to use an acyclic aliphatic diol with a linear structure having 4 or less carbon atoms, and it is particularly preferable to use an acyclic aliphatic diol with a linear structure having 2 to 3 carbon atoms. Examples of the acyclic aliphatic diol with a linear structure having 4 or less carbon atoms include ethylene glycol, 1,3-propanediol, and 1,4-butanediol. That is, when an aliphatic polyol with a small carbon number of 4 or less is used, the weight ratio of carboxylic acids with a high biomass degree in the polyester resin (A) increases, thereby increasing the biomass degree.

[0048] [Production of polyester resin (A)] In the present invention, the polyester resin (A) can be produced by polycondensation of a polycarboxylic acid, a polyol, and a thermoplastic polyester resin in the presence of a catalyst by a known method, and in the polycondensation reaction, an esterification reaction or an ester exchange reaction is carried out first, followed by the polycondensation reaction. When a high molecular weight is not required, the polyester resin (A) may be produced by only an esterification reaction or an ester exchange reaction.

[0049] In such an esterification reaction or transesterification reaction, a catalyst is used, and specific examples include titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate, antimony-based catalysts such as antimony trioxide, germanium-based catalysts such as germanium dioxide, and catalysts such as zinc acetate, manganese acetate, and dibutyltin oxide, and one or more of these are used. Among these, antimony trioxide, tetrabutyl titanate, germanium dioxide, and zinc acetate are preferred from the standpoint of the balance between high catalytic activity and the hue of the resulting reaction product.

[0050] The amount of the catalyst to be added is preferably 1 to 10,000 ppm, particularly preferably 10 to 5,000 ppm, and further preferably 20 to 3,000 ppm, based on the total weight of the copolymerization components. If the amount is too small, the polymerization reaction tends to proceed insufficiently, whereas if the amount is too large, there is no advantage such as shortening the reaction time, and side reactions tend to occur easily.

[0051] The reaction temperature during the esterification reaction is preferably 200 to 300°C, particularly preferably 210 to 280°C, and even more preferably 220 to 260°C. If the reaction temperature is too low, the reaction tends to proceed insufficiently, while if it is too high, side reactions such as decomposition tend to occur. The pressure during the reaction is usually normal pressure.

[0052] As reaction conditions for the polycondensation reaction carried out after the above-mentioned esterification reaction or transesterification reaction, it is preferable to further blend the same amount of the same catalyst as used in the above-mentioned esterification reaction or transesterification reaction, set the reaction temperature preferably to 200 to 280°C, particularly preferably 210 to 270°C, and gradually reduce the pressure of the reaction system until the reaction is finally carried out at 5 hPa or less. If the reaction temperature is too low, the reaction will not proceed sufficiently and it will be difficult to reach the desired molecular weight, whereas if the reaction temperature is too high, side reactions such as decomposition will tend to occur easily.

[0053] Thus, a polyester resin (A) containing structural units derived from the compound (a1) and structural units derived from the aromatic compound (a2) is obtained.

[0054] The number average molecular weight of the polyester resin (A) used in the present invention is characterized by being 3000 or more, and is preferably 3500 to 50000, more preferably 4000 to 40000, particularly preferably 5000 to 30000, especially preferably 6000 to 20000, and most preferably 7000 to 15000. If the number average molecular weight is too large, handling properties will decrease, requiring a large amount of solvent and tending to increase the environmental load, while if the number average molecular weight is too small, adhesive properties will tend to decrease.

[0055] The weight-average molecular weight of the polyester resin (A) is preferably 10,000 or more, more preferably 10,000 to 500,000, even more preferably 20,000 to 300,000, particularly preferably 30,000 to 250,000, especially preferably 40,000 to 200,000, and most preferably 50,000 to 150,000. If the weight-average molecular weight is too large, handling properties will be reduced, requiring a large amount of solvent and the environmental load will tend to increase, whereas if the weight-average molecular weight is too small, adhesive properties will tend to decrease.

[0056] The number-average molecular weight and weight-average molecular weight mentioned above are number-average molecular weight and weight-average molecular weight converted into standard polystyrene molecular weight. A high-performance liquid chromatograph (manufactured by Tosoh Corporation, "HLC-8320GPC") was used with a column: TSKgel SuperMultipore HZ-M (exclusion limit molecular weight: 2 × 10 6 The measurement is performed using two columns in series (theoretical plate number: 16,000 / column, filler material: styrene-divinylbenzene copolymer, filler particle size: 4 μm).

[0057] In the present invention, in order to achieve excellent adhesive strength and holding power, the ratio (X1 / X2) of the molar concentration (X1) of structural units derived from at least one compound (a1) selected from dimer acid and dimer diol to the molar concentration (X2) of structural units derived from aromatic compound (a2) in the polyester resin (A) is preferably greater than 2.0. It is more preferably 2.2 or greater, even more preferably 2.3 or greater, particularly preferably 2.5 or greater, and especially preferably 3.0 or greater. If X1 / X2 is 2.0 or less, adhesive strength and holding power decrease. The upper limit of X1 / X2 is usually 20, preferably 10, more preferably 6.0, even more preferably 5.0, particularly preferably 4.0, and especially preferably 3.5. When compound (a1) contains an aromatic ring, it is considered to be included in compound (a1) but not in aromatic compound (a2).

[0058] The content of structural units derived from compound (a1) in the polyester resin (A) is preferably 50 to 99 mol %, more preferably 60 to 97 mol %, even more preferably 65 to 95 mol %, and particularly preferably 70 to 90 mol % of the total. If this content is too low, the polyester resin (A) tends to be too hard and have reduced adhesive strength. If this content is too high, the polyester resin (A) tends to be too soft and have slightly reduced adhesive properties.

[0059] Furthermore, when the polyester resin (A) contains structural units derived from an aliphatic polyol, the content of acyclic aliphatic diols having 2 to 20 carbon atoms among the structural units derived from the aliphatic polyol is preferably 10 mol % or more, more preferably 30 mol % or more, and particularly preferably 50 mol % or more, from the viewpoint of the initial adhesive strength when used as an adhesive.

[0060] The biomass ratio of the polyester resin (A) is usually 50% or more, preferably 60% or more, more preferably 70% or more, particularly preferably 80% or more, particularly preferably 85% or more, and most preferably 90% or more. The upper limit is 100%. If the biomass ratio is low, the reduction of the environmental load tends to be insufficient.

[0061] Here, the biomass content of the polyester resin (A) refers to the weight ratio of the plant-derived raw materials used in producing the polyester resin (A) incorporated into the resin relative to the total weight of the polyester resin (A). The biomass degree of the polycarboxylic acids and polyols is determined from the weighted average of the respective biomass degrees. In addition, the value obtained by any of the following calculation methods may be within the above range.

[0062] (Calculation method) <When polycondensation reaction occurs> Biomass ratio (%) = [(number of moles of carbon of plant-derived monomer calculated from the molar ratio of polycarboxylic acids and polyol in polyester resin (A)) / (number of moles of carbon of all constituent monomers in polyester resin (A))] × 100

[0063] <When no polycondensation reaction is involved> Biomass ratio (%) = [(number of moles of carbon of plant-derived monomer in polyester resin (A)) / (number of moles of carbon of all constituent monomers in polyester resin (A))] × 100

[0064] The biomass ratio can also be determined by analyzing the composition ratio by NMR and calculating the carbon number of the plant-derived monomer / total carbon number.

[0065] Furthermore, the biomass degree can also be measured by the method described in "Technology for Determining the Origin of Biofuels Using Natural Radioactive Carbon C-14," Tokyo Metropolitan Industrial Technology Research Center Research Report, No. 4, 2009.

[0066] Methods for adjusting the biomass degree within a predetermined range include using mainly plant-derived polycarboxylic acids or plant-derived polyols, but it is particularly preferable to use plant-derived polycarboxylic acids, as this allows for an efficient increase in the biomass degree.

[0067] In the present invention, the recycled carbon usage rate of the polyester resin (A) is preferably 50% or more from the viewpoint of reducing the environmental load, more preferably 60% or more, even more preferably 70% or more, particularly preferably 80% or more, especially preferably 85% or more, and most preferably 90% or more, with the upper limit being 100%. Here, the recycled carbon content of the polyester resin (A) refers to the weight ratio of raw materials containing recycled carbon used in producing the polyester resin (A) relative to the total weight of the polyester resin (A). Examples of raw materials containing recycled carbon include thermoplastic polyester resins such as plant-derived raw materials and recycled polyethylene terephthalate (recycled PET).

[0068] The recycled carbon usage rate can be calculated in the same way as the biomass degree calculation method described above, that is, as follows. (Calculation method) <When polycondensation reaction occurs> Recycled carbon usage rate (%) = [(number of moles of recycled carbon calculated from the molar ratio of polycarboxylic acids and polyol in polyester resin (A)) / (number of moles of carbon of all constituent monomers in polyester resin (A))] × 100

[0069] <When no polycondensation reaction is involved> Recycled carbon usage rate (%) = [(number of moles of recycled carbon in polyester resin (A)) / (number of moles of carbon in all constituent monomers in polyester resin (A))] × 100

[0070] The glass transition temperature (Tg) of the polyester resin (A) is preferably −90 to 20° C., particularly preferably −60 to 0° C., and further preferably −50 to −20° C. If the glass transition temperature (Tg) is too high, the adhesiveness when used as a pressure-sensitive adhesive tends to decrease, whereas if it is too low, the heat resistance and cohesive strength tend to decrease.

[0071] The glass transition temperature (Tg) is measured using a differential scanning calorimeter DSC Q20 manufactured by TA Instruments, Inc. The measurement temperature range is −90 to 100° C., and the temperature rise rate is 10° C. / min.

[0072] The ester group concentration of the polyester resin (A) is usually 2 mmol / g or more, preferably 3 to 10 mmol / g, more preferably 3.6 to 6 mmol / g, and particularly preferably 4.2 to 5 mmol / g. If the ester group concentration is too low, the polyester resin (A) becomes soft and tends to have reduced adhesive properties.

[0073] The ester group concentration (mmol / g) refers to the number of moles of ester bonds in 1 g of polyester resin (A), and is calculated from the amounts charged, for example. The calculation method is to divide the number of moles of the carboxylic acid or polyol, whichever is charged in smaller amounts, by the total weight, and an example of the calculation formula is shown below. When the polycarboxylic acids and polyol are charged in equal molar amounts, either of the following calculation formulas may be used. Furthermore, when a monomer having both a carboxyl group and a hydroxyl group is used, or when polyester is produced from caprolactone or the like, the calculation method will be changed appropriately.

[0074] <When polycarboxylic acids are in small amounts> Ester group concentration (mmol / g) = [(A1 / a1 × m1 + A2 / a2 × m2 + A3 / a3 × m3 ) / Z] × 1000 A1, A2, A3: Amount of polycarboxylic acids (g) a1, a2, a3: molecular weight of polycarboxylic acids m1, m2, m3: Number of carboxyl groups per molecule of polycarboxylic acids Z: Finished weight (g)

[0075] <When there is little polyol> Ester group concentration (mmol / g) = [(B1 / b1 × n1 + B2 / b2 × n2 + B3 / b3 × n3 ) / Z] × 1000 B1, B2, B3: Amount of polyol (g) b1, b2, b3: molecular weight of polyol n1, n2, n3: number of hydroxyl groups per polyol molecule Z: Finished weight (g)

[0076] The ester group concentration can also be measured by a known method using NMR etc. For example, the ester group concentration of the polyester resin (A) can be measured by NMR at a resonance frequency of 400 MHz. 1 H-NMR measurement (proton nuclear magnetic resonance spectroscopy), 13 This can be done by C-NMR measurement (carbon-type nuclear magnetic resonance spectroscopy).

[0077] Examples of methods for adjusting the ester group concentration include selecting a polyol having 4 or less carbon atoms as the polyol, increasing the content of linear carboxylic acids as the polycarboxylic acids, and combining both of these methods.

[0078] The heat of crystalline fusion of the polyester resin (A) measured with a differential scanning calorimeter is usually 10 J / g or less, preferably 5 J / g or less, more preferably 2 J / g or less, and particularly preferably no heat of crystalline fusion. If the heat of crystalline fusion is too large, crystallinity will occur, which tends to reduce the storage stability of the resin solution and reduce the stability and adhesive properties at low temperatures when made into a pressure-sensitive adhesive sheet. The heat of crystalline fusion is the energy consumed when a crystallized substance is heated and melted, and can be measured by a differential scanning calorimeter (DSC).

[0079] Examples of methods for adjusting the heat of crystalline fusion include a method of appropriately using polycarboxylic acids having an alkyl group on the side chain or a polyol having an alkyl group on the side chain, and a method of using three or more, preferably four or more, copolymerizable monomer components.

[0080] The acid value of the polyester resin (A) is preferably 10 mgKOH / g or less in order to prevent hydrolysis and improve durability, more preferably 5 mgKOH / g or less, and particularly preferably 2 mgKOH / g or less. If the acid value is too high, durability tends to decrease. The acid value can be adjusted, for example, by increasing the proportion of polyol during the esterification reaction or transesterification reaction, or by adjusting the reaction conditions. The lower limit of the acid value is usually 0 mgKOH / g.

[0081] The acid value of the polyester resin (A) is determined by neutralization titration in accordance with JIS K0070. The acid value in the present invention means the content of carboxy groups in the polyester resin (A). The carboxy groups include those in a carboxylate ion state in which the carboxy groups are neutralized with a basic compound.

[0082] The polyester resin composition of the present invention preferably contains, in addition to the polyester resin (A), a polyvalent isocyanate compound (B), a hydrolysis inhibitor (C), and, as necessary, a tackifier (D), a urethanization catalyst (E), an antioxidant (F), and the like.

[0083] <Polyisocyanate Compound (B)> It is preferable that the polyester resin composition of the present invention further contains a polyisocyanate compound (B) as a crosslinking agent. By containing the polyisocyanate compound (B), the polyester resin (A) is crosslinked with the polyisocyanate compound (B), resulting in an excellent cohesive strength and improved performance as a pressure-sensitive adhesive.

[0084] Examples of such polyisocyanate compounds (B) include aromatic isocyanate crosslinking agents such as tolylene diisocyanate crosslinking agents such as 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, xylylene diisocyanate crosslinking agents such as 1,3-xylylene diisocyanate, diphenylmethane crosslinking agents such as diphenylmethane-4,4-diisocyanate, and naphthalene diisocyanate crosslinking agents such as 1,5-naphthalene diisocyanate; isophorone diisocyanate, 1,4-cyclohexane diisocyanate, 4,4'-dicyclohexyl methyl ... Examples of suitable crosslinking agents include alicyclic isocyanate crosslinking agents such as hexane diisocyanate, methylcyclohexane diisocyanate, isopropylidenedicyclohexyl-4,4'-diisocyanate, 1,3-diisocyanatomethylcyclohexane, and norbornane diisocyanate; aliphatic isocyanate crosslinking agents such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate; and adducts of the above isocyanate compounds with polyol compounds such as trimethylolpropane, as well as biuret and isocyanurate forms of these isocyanate compounds. The polyisocyanate compounds may also be used in which the isocyanate moiety is blocked with phenol, lactam, or the like. These polyisocyanate compounds may be used alone or in combination.

[0085] The content of the polyisocyanate compound (B) can be appropriately selected depending on the molecular weight of the polyester resin (A) and the intended use, but it is usually preferable that the polyisocyanate compound (B) is contained in a proportion such that the reactive group contained in the polyisocyanate compound (B) is 0.2 to 10 equivalents per equivalent of at least one of the hydroxyl group and the carboxyl group contained in the polyester resin (A), particularly preferably 0.5 to 5 equivalents, and even more preferably 0.5 to 3 equivalents. If the equivalent number of the reactive group contained in the polyisocyanate compound (B) is too small, the cohesive strength tends to decrease, and if it is too large, the flexibility tends to decrease.

[0086] In the reaction between the polyester resin (A) and the polyisocyanate compound (B), organic solvents that do not have functional groups that react with the components (A) and (B), such as esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and aromatics such as toluene and xylene, can be used. These can be used alone or in combination of two or more.

[0087] <Hydrolysis inhibitor (C)> The hydrolysis inhibitor (C) is contained in order to ensure the long-term durability of the polyester resin composition. As the hydrolysis inhibitor (C), a conventionally known compound can be used, for example, a compound that reacts with the carboxyl terminal of the polyester resin (A) to bond, specifically, for example, a compound containing a functional group such as a carbodiimide group, an epoxy group, an oxazoline group, etc. Among these, a carbodiimide group-containing compound is preferred because it is highly effective in eliminating the catalytic activity of protons derived from the carboxyl terminal.

[0088] As the carbodiimide group-containing compound, a known carbodiimide having one or more carbodiimide groups (-N=C=N-) in the molecule is usually used. However, in order to improve durability under high temperature and high humidity, a compound having two or more carbodiimide groups in the molecule, i.e., a polyvalent carbodiimide compound, is preferred. In particular, a compound having three or more, preferably five or more, and especially seven or more carbodiimide groups in the molecule is preferred. The number of carbodiimide groups in the molecule is usually 50 or less; if there are too many carbodiimide groups, the molecular structure becomes too large, which tends to reduce compatibility. It is also preferred to use a high-molecular-weight polycarbodiimide produced by decarboxylation condensation reaction of diisocyanate in the presence of a carbodiimidization catalyst.

[0089] Furthermore, in terms of storage stability, it is preferable that the terminal isocyanate groups of the high-molecular-weight polycarbodiimide be blocked with a blocking agent. Examples of blocking agents include compounds having active hydrogen that reacts with isocyanate groups, or compounds having an isocyanate group. Examples include monoalcohols, monocarboxylic acids, monoamines, and monoisocyanates each having one substituent selected from a carboxy group, an amino group, and an isocyanate group.

[0090] Examples of such high molecular weight polycarbodiimides include those obtained by subjecting the following diisocyanates to a decarboxylation condensation reaction.

[0091] Examples of such diisocyanates include 4,4'-diphenylmethane diisocyanate, 3,3'-dimethoxy-4,4'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 4,4'-diphenylether diisocyanate, 3,3'-dimethyl-4,4'-diphenylether diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and tetramethylxylylene diisocyanate. These can be used alone or in combination of two or more. Such high molecular weight polycarbodiimides can be synthesized or commercially available products can be used.

[0092] Commercially available examples of the carbodiimide group-containing compound include the Carbodilite (registered trademark) series manufactured by Nisshinbo Chemical Inc. Among these, Carbodilite (registered trademark) V-01, V-02B, V-03, V-04K, V-04PF, V-05, V-07, V-09, and V-09GB are preferred because of their excellent compatibility with organic solvents.

[0093] As the epoxy group-containing compound, for example, a glycidyl ester compound or a glycidyl ether compound is preferred.

[0094] Specific examples of the glycidyl ester compound include benzoic acid glycidyl ester, t-Bu-benzoic acid glycidyl ester, p-toluic acid glycidyl ester, cyclohexanecarboxylic acid glycidyl ester, pelargonic acid glycidyl ester, stearic acid glycidyl ester, lauric acid glycidyl ester, palmitic acid glycidyl ester, behenic acid glycidyl ester, versatic acid glycidyl ester, oleic acid glycidyl ester, linoleic acid glycidyl ester, linolenic acid glycidyl ester, behenolic acid glycidyl ester, stearolic acid glycidyl ester, terephthalic acid diglycidyl ester, and isophthalic acid. Examples of the diglycidyl ester include diglycidyl ester, diglycidyl phthalate, diglycidyl naphthalenedicarboxylic acid, diglycidyl ester of methyl terephthalate, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, diglycidyl ester of cyclohexanedicarboxylic acid, diglycidyl ester of adipic acid, diglycidyl ester of succinic acid, diglycidyl ester of sebacic acid, diglycidyl ester of dodecanedioic acid, diglycidyl ester of octadecanedicarboxylic acid, triglycidyl trimellitate, and tetraglycidyl ester of pyromellitic acid. These may be used alone or in combination of two or more.

[0095] Specific examples of the glycidyl ether compound include phenyl glycidyl ether, o-phenyl glycidyl ether, 1,4-bis(β,γ-epoxypropoxy)butane, 1,6-bis(β,γ-epoxypropoxy)hexane, 1,4-bis(β,γ-epoxypropoxy)benzene, 1-(β,γ-epoxypropoxy)-2-ethoxyethane, 1-(β,γ-epoxypropoxy)-2-benzyloxyethane, 2,2-bis-[p-(β,γ-epoxypropoxy)phenyl]propane, and bisglycidyl polyethers obtained by reacting bisphenols such as 2,2-bis-(4-hydroxyphenyl)propane and 2,2-bis-(4-hydroxyphenyl)methane with epichlorohydrin, and these can be used alone or in combination of two or more.

[0096] The oxazoline group-containing compound is preferably a bisoxazoline compound, etc. Specific examples include 2,2'-bis(2-oxazoline), 2,2'-bis(4-methyl-2-oxazoline), 2,2'-bis(4,4-dimethyl-2-oxazoline), 2,2'-bis(4-ethyl-2-oxazoline), 2,2'-bis(4,4'-diethyl-2-oxazoline), 2,2'-bis(4-propyl-2-oxazoline), 2,2'-bis(4-butyl-2-oxazoline), 2,2'-bis(4-hexyl-2-oxazoline), 2,2'-bis(4-phenyl-2-oxazoline), 2,2'-bis(4-cyclohexyl-2-oxazoline), 2,2'-bis(4-benzyl-2-oxazoline), 2,2'-p-phenylenebis(2-oxazoline), 2,2'-m-phenylenebis(2-oxazoline), 2,2'-o-phenylenebis(2-oxazoline), 2,2'-p-phenylenebis(4-methyl-2-oxazoline), 2,2'-p-phenylenebis(4,4-dimethyl-2-oxazoline) 2,2'-m-phenylenebis(4-methyl-2-oxazoline), 2,2'-m-phenylenebis(4,4-dimethyl-2-oxazoline), 2,2'-ethylenebis(2-oxazoline), 2,2'-tetramethylenebis(2-oxazoline), 2,2'-hexamethylenebis(2-oxazoline), 2,2'-octamethylenebis(2-oxazoline), 2,2'-decamethylenebis(2-oxazoline), 2,2'-ethylene Examples of suitable terpolymers include 2,2'-tetramethylenebis(4,4-dimethyl-2-oxazoline), 2,2'-9,9'-diphenoxyethanebis(2-oxazoline), 2,2'-cyclohexylenebis(2-oxazoline), and 2,2'-diphenylenebis(2-oxazoline). Among these, 2,2'-bis(2-oxazoline) is most preferred in terms of reactivity with the polyester resin (A). These may be used alone or in combination of two or more.

[0097] The hydrolysis inhibitor (C) preferably has low volatility, and therefore preferably has a high number average molecular weight. The number average molecular weight is usually 300 to 10,000, preferably 1,000 to 5,000. Furthermore, from the viewpoint of hydrolysis resistance, it is preferable to use a hydrolysis inhibitor (C) having a high weight-average molecular weight. The weight-average molecular weight of the hydrolysis inhibitor (C) is preferably 500 or more, more preferably 1000 or more, even more preferably 2000 or more, and particularly preferably 3000 or more. The upper limit of the weight-average molecular weight is usually 50,000. If the molecular weight of the hydrolysis inhibitor (C) is too small, the hydrolysis resistance tends to decrease, whereas if the molecular weight is too large, the compatibility with the polyester resin (A) tends to decrease.

[0098] Among the hydrolysis inhibitors (C), it is preferable to use a carbodiimide group-containing compound, and in this case, the carbodiimide equivalent is preferably 50 to 10,000, particularly 100 to 1,000, and further preferably 150 to 500. The carbodiimide equivalent indicates the chemical formula weight per carbodiimide group.

[0099] The content of the hydrolysis inhibitor (C) is preferably 0.01 to 10 parts by weight, particularly preferably 0.1 to 5 parts by weight, and even more preferably 0.2 to 3 parts by weight, relative to 100 parts by weight of the polyester resin (A). If the content is too high, turbidity tends to occur due to poor compatibility with the polyester resin (A), while if the content is too low, sufficient durability tends to be difficult to obtain.

[0100] The content of the hydrolysis inhibitor (C) is preferably optimized depending on the acid value of the polyester resin (A), and the molar ratio [(y) / (x)] of the total number of moles (y) of functional groups of the hydrolysis inhibitor (C) in the polyester resin composition to the total number of moles (x) of acidic functional groups of the polyester resin (A) in the polyester resin composition is preferably 0.5≦(y) / (x), particularly preferably 1≦(y) / (x)≦1000, and even more preferably 1.5≦(y) / (x)≦100. If the molar ratio of (y) to (x) is too low, the moisture and heat resistance tends to decrease, whereas if the molar ratio of (y) to (x) is too high, the compatibility with the polyester resin (A) tends to decrease, and the adhesive strength, cohesive strength, and durability tend to decrease.

[0101] <Tackifier (D)> In the present invention, it is preferable to contain a tackifier (D) in order to improve adhesive properties.

[0102] The tackifier (D) is not particularly limited, and conventionally known tackifiers can be used. Examples of the tackifier (D) include hydrocarbon tackifier resins, terpene resins, phenolic resins, rosin resins, xylene resins, epoxy resins, polyamide resins, ketone resins, and elastomer resins. These may be used alone or in combination of two or more. Of these, hydrocarbon tackifier resins and terpene resins are preferred. It is particularly preferred that the tackifier (D) contains at least one hydrocarbon tackifier resin, and the hydrocarbon tackifier resin preferably accounts for 30% by weight or more, preferably 50% by weight or more, and more preferably 70% by weight or more of the total tackifier.

[0103] Examples of the hydrocarbon tackifying resin include various hydrocarbon resins such as aliphatic hydrocarbon resins, aromatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aliphatic-aromatic petroleum resins (such as styrene-olefin copolymers), aliphatic-alicyclic petroleum resins, hydrogenated hydrocarbon resins, coumarone resins, and coumarone-indene resins. Commercially available products include "FTR6100," "FTR6110," "FTR6125," "FTR8100," "FTR8120," and "FMR0150" manufactured by Mitsui Chemicals, Inc.

[0104] Examples of the terpene resin include terpene resins, terpene phenol resins, and aromatic-modified terpene resins. Specific examples include α-pinene polymers, β-pinene polymers, dipentene polymers, and terpene resins obtained by phenol-modifying, aromatic-modifying, hydrogenating, or hydrocarbon-modifying these polymers. Commercially available products include "YS Polystar S145," "YS Resin PX1000," "YS Resin PX1250," "YS Polystar T160," "YS Polystar T145," "YS Polystar T130," "YS Resin TO115," "YS Polystar G150," "YS Polystar G125," "YS Polystar U130," and "Clearon P125," manufactured by Yasuhara Chemical Co., Ltd. Terpene resins are preferred due to their excellent adhesion to non-polar substrates such as polypropylene.

[0105] Examples of the phenolic resin that can be used include condensates of formaldehyde with various phenols such as phenol, m-cresol, 3,5-xylenol, p-alkylphenol, and resorcinol. Furthermore, resols obtained by subjecting the phenols and formaldehyde to an addition reaction in the presence of an alkali catalyst, novolaks obtained by subjecting the phenols and formaldehyde to a condensation reaction in the presence of an acid catalyst, and rosin-modified phenolic resins obtained by subjecting rosins, such as unmodified or modified rosin or derivatives thereof, to addition with phenol in the presence of an acid catalyst, followed by thermal polymerization, can also be used.

[0106] Examples of the rosin resin include rosin resin, polymerized rosin resin, hydrogenated rosin resin, rosin ester resin, hydrogenated rosin ester resin, rosin phenolic resin, polymerized rosin ester, etc. Specific examples include unmodified rosins (raw rosins) such as gum rosin, wood rosin, and tall oil rosin, modified rosins obtained by hydrogenating, disproportionating, polymerizing, or otherwise chemically modifying these, and derivatives of these. Commercially available products include, for example, Hariestar TF, Haritack 8LJA, Haritack PH, Haritack FK100, and Haritack PCJ manufactured by Harima Chemicals.

[0107] The tackifier (D) preferably has an acid value of 30 mgKOH / g or less, particularly 10 mgKOH / g or less, further preferably 6 mgKOH / g or less, and particularly preferably 3 mgKOH / g or less. When multiple types of tackifiers (D) are used in combination, the average thereof is preferably within the above range.

[0108] The softening point of the tackifier (D) (measured, for example, by the ring and ball method) is preferably 80 to 170° C., particularly 90 to 160° C., more preferably 100 to 150° C., even more preferably 120 to 155° C., and particularly preferably 135 to 150° C. If the softening point is within the above range, the adhesive properties (adhesive strength, cohesive strength) can be improved, which is preferable.

[0109] In the present invention, the tackifier (D) is preferably a plant-derived tackifier in order to maintain a high biomass content in the entire polyester resin composition. Examples of plant-derived tackifiers include terpene resins and rosin resins.

[0110] The content of the tackifier (D) is preferably 2 to 200 parts by weight, more preferably 5 to 150 parts by weight, even more preferably 8 to 100 parts by weight, particularly preferably 10 to 80 parts by weight, and most preferably 20 to 50 parts by weight, relative to 100 parts by weight of the polyester resin (A). When the content is within the above range, adhesive properties (adhesive strength, cohesive strength) tend to be improved.

[0111] <Urethanization catalyst (E)> The polyester resin composition of the present invention preferably contains a urethanization catalyst (E) from the viewpoint of reaction rate.

[0112] Examples of the urethanization catalyst (E) include organometallic compounds, tertiary amine compounds, etc. These can be used alone or in combination of two or more kinds.

[0113] Examples of the organometallic compounds include zirconium compounds, iron compounds, tin compounds, titanium compounds, lead compounds, cobalt compounds, and zinc compounds. Examples of zirconium compounds include zirconium naphthenate and zirconium acetylacetonate. Examples of iron compounds include iron acetylacetonate and iron 2-ethylhexanoate. Examples of tin compounds include dibutyltin dichloride, dibutyltin oxide, and dibutyltin dilaurate.

[0114] Examples of titanium compounds include dibutyltitanium dichloride, tetrabutyltitanate, and butoxytitanium trichloride. Examples of lead compounds include lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate. Examples of cobalt-based compounds include cobalt 2-ethylhexanoate and cobalt benzoate. Examples of zinc compounds include zinc naphthenate and zinc 2-ethylhexanoate. Examples of the tertiary amine compound include triethylamine, triethylenediamine, and 1,8-diazabicyclo-(5,4,0)-undecene-7.

[0115] Among these urethanization catalysts (E), organometallic compounds are preferred, and zirconium compounds are particularly preferred, in terms of reaction rate and pot life of the adhesive layer. Furthermore, the urethanization catalyst (E) is preferably used in combination with acetylacetone as a catalytic inhibitor. The inclusion of acetylacetone is preferred in that it inhibits catalytic activity at low temperatures and extends pot life.

[0116] The content of the urethanization catalyst (E) is preferably 0.0001 to 1 part by weight, particularly 0.001 to 0.1 part by weight, and even more preferably 0.01 to 0.05 part by weight, per 100 parts by weight of the polyester resin (A). If the content is too low, the aging time until the crosslinking reaction is completed tends to be long, while if the content is too high, the adhesive properties tend to decrease.

[0117] <Antioxidant (F)> The polyester resin composition of the present invention preferably contains an antioxidant (F) in order to improve the stability of the resin.

[0118] Examples of the antioxidant (F) include hindered phenol-based antioxidants, amine-based antioxidants, sulfur-based antioxidants, phosphoric acid-based antioxidants, etc. Among these, at least one selected from the group consisting of hindered phenol-based antioxidants, amine-based antioxidants, and phosphoric acid-based antioxidants is preferred, and antioxidants consisting of hindered phenol-based compounds are particularly preferred. Examples of hindered phenol-based antioxidants include antioxidants having a hindered phenol structure in which a group with large steric hindrance, such as a tertiary butyl group, is bonded to at least one of the carbon atoms adjacent to the carbon atom on the aromatic ring to which the phenolic hydroxyl group is bonded.

[0119] The content of the antioxidant (F) is preferably 0.01 to 10 parts by weight, more preferably 0.03 to 8 parts by weight, and even more preferably 0.05 to 5 parts by weight, based on 100 parts by weight of the polyester resin (A). If the content is too low, adhesive residue on the adherend tends to occur, whereas if the content is too high, adhesive properties tend to decrease.

[0120] In addition to the polyester resin (A), polyisocyanate compound (B), hydrolysis inhibitor (C), tackifier (D), urethanization catalyst (E), and antioxidant (F), the polyester resin composition of the present invention may contain additives such as softeners, ultraviolet absorbers, stabilizers, and antistatic agents, as well as inorganic or organic fillers, metal powders, pigments, and other powdery or particulate additives, provided that the effects of the present invention are not impaired. Furthermore, the polyester resin composition may contain small amounts of impurities contained in the raw materials used to produce the polyester resin composition. These may be used alone or in combination of two or more.

[0121] Such a polyester resin composition can be obtained, for example, by preparing the polyester resin (A) and necessary optional components, etc., and blending and dispersing them during the production of the polyester resin (A), or by blending them into a solution of the polyester resin (A) dissolved in an organic solvent and dispersing them using a mixing roller.

[0122] The polyester resin composition of the present invention preferably has a biomass degree of 50% or more in terms of reducing the environmental load, more preferably 60% or more, even more preferably 70% or more, particularly preferably 80% or more, especially preferably 85% or more, and most preferably 90% or more. The biomass degree of the polyester resin composition can be adjusted by adjusting the types and amounts of the polyester resin (A) and other blending components. The biomass degree of the polyester resin composition is the ratio of the weight of plant-derived raw materials used in producing the polyester resin composition to the total weight of the polyester resin composition, and can be calculated, for example, by the following formula. Biomass content (%) = [(biomass content of each plant-derived raw material used in producing the polyester-based resin composition) × (total weight of each plant-derived raw material used in producing the polyester-based resin composition)] / (total weight of the polyester-based resin composition).

[0123] The biomass degree of the polyester resin composition can also be measured by the aforementioned method using NMR or the method using natural radioactive carbon C-14. The value obtained by any of the above calculation methods may be within the above range.

[0124] In terms of reducing the environmental load, the polyester resin composition of the present invention preferably has a recycled carbon usage rate of 50% or more, more preferably 60% or more, even more preferably 70% or more, particularly preferably 80% or more, especially preferably 85% or more, and most preferably 90% or more, with the upper limit being 100%. Here, the recycled carbon content of the polyester resin composition is the ratio by weight of raw materials containing recycled carbon used in producing the polyester resin composition to the total weight of the polyester resin composition, and examples of raw materials containing recycled carbon include plant-derived raw materials, recycled polyethylene terephthalate (recycled PET), etc. The recycled carbon content of the polyester resin composition can be adjusted by adjusting the types and amounts of the polyester resin (A) and other blending components. The recycled carbon usage rate of the polyester resin composition can be calculated, for example, by the following formula. Recycled carbon usage rate (%) = [(recycled carbon usage rate of each plant-derived raw material used in producing the polyester-based resin composition) × (total of (weight of each raw material using recycled carbon used in producing the polyester-based resin composition)] / (total weight of the polyester-based resin composition)

[0125] The pressure-sensitive adhesive composition of the present invention contains the polyester resin composition, and preferably consists of the polyester resin composition alone. The pressure-sensitive adhesive according to the present invention is obtained by crosslinking the pressure-sensitive adhesive composition.

[0126] The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive, and the pressure-sensitive adhesive layer is preferably formed on one or both sides of a supporting substrate. In the present invention, the term "sheet" is used to include "film" and "tape."

[0127] <Adhesive sheet> The pressure-sensitive adhesive sheet can be produced, for example, as follows. Such a pressure-sensitive adhesive sheet can be produced according to a known general method for producing a pressure-sensitive adhesive sheet. For example, the pressure-sensitive adhesive composition is applied to a substrate, dried, a release sheet is attached to the opposite surface of the pressure-sensitive adhesive layer, and the substrate is cured as necessary to obtain the pressure-sensitive adhesive sheet of the present invention having a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive on the substrate.

[0128] Alternatively, the pressure-sensitive adhesive sheet of the present invention can be obtained by coating the pressure-sensitive adhesive composition on a release sheet, drying it, laminating a substrate to the opposite side of the pressure-sensitive adhesive layer, and curing if necessary.

[0129] Alternatively, a substrate-less double-sided PSA sheet can be produced by forming a PSA layer on a release sheet and then laminating another release sheet to the opposite side of the PSA layer.

[0130] When using the obtained pressure-sensitive adhesive sheet or substrate-less double-sided pressure-sensitive adhesive sheet, the release sheet is peeled off from the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer is then attached to an adherend.

[0131] Examples of the substrate include polyester resins such as polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate / isophthalate copolymer; polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; polyethylene fluoride resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyethylene fluoride; polyamides such as nylon 6 and nylon 6,6; vinyl polymers such as polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, and vinylon; cellulose resins such as cellulose triacetate and cellophane; acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate; polystyrene; polycarbonate; polyarylate; polyimide; and sheets made of at least one synthetic resin selected from the group consisting of cycloolefin polymers and the like; metal foils of aluminum, copper, and iron; paper such as fine paper and glassine paper; and woven and nonwoven fabrics made of glass fiber, natural fiber, synthetic fiber, and the like. These substrates can be used as a single layer or as a multi-layer structure in which two or more types are laminated.

[0132] Among these, substrates made of polyethylene terephthalate and polyimide are particularly preferred, with polyethylene terephthalate being particularly preferred in terms of its excellent adhesiveness to pressure-sensitive adhesives.

[0133] The substrate may also be a foam substrate, such as a foam sheet made of a synthetic resin foam such as polyurethane foam, polyethylene foam, polyacrylate foam, etc. Among these, polyethylene foam and polyacrylate foam are preferred because they have an excellent balance between conformability to the adherend and adhesive strength.

[0134] The thickness of the substrate is, for example, preferably from 1 to 1000 μm, particularly preferably from 2 to 500 μm, and further preferably from 3 to 300 μm.

[0135] As the release sheet, for example, a sheet made of any of the various synthetic resins exemplified above as the substrate, paper, cloth, nonwoven fabric, etc. that has been subjected to a release treatment can be used. As the release sheet, it is preferable to use a silicone-based release sheet.

[0136] The pressure-sensitive adhesive composition may be applied using, for example, a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater, comma coater, or the like.

[0137] The conditions for the aging treatment are generally room temperature (23°C) to 70°C, and the time is generally 1 to 30 days. Specifically, the treatment may be carried out under conditions such as 1 to 20 days at 23°C, preferably 3 to 14 days at 23°C, or 1 to 10 days at 40°C.

[0138] As for drying conditions, the drying temperature is preferably 60 to 140° C., particularly preferably 80 to 120° C., and the drying time is preferably 0.5 to 30 minutes, particularly preferably 1 to 5 minutes.

[0139] The thickness of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet and substrate-less double-sided pressure-sensitive adhesive sheet is preferably 2 to 500 μm, particularly preferably 5 to 200 μm, and even more preferably 10 to 100 μm. If the thickness of the pressure-sensitive adhesive layer is too thin, the adhesive strength tends to decrease, while if it is too thick, it becomes difficult to apply uniformly and problems such as air bubbles entering the coating film tend to occur. When considering impact absorption properties, a thickness of 50 μm or more is preferable.

[0140] The thickness of the adhesive layer is determined by subtracting the measured thickness of the constituent members other than the adhesive layer from the measured thickness of the entire adhesive sheet using a Mitutoyo ID-C112B.

[0141] The gel fraction of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is preferably 10% by weight or more, particularly preferably 20 to 80% by weight, and even more preferably 30 to 70% by weight, from the viewpoints of durability and adhesive strength. If the gel fraction is too low, the cohesive strength tends to decrease, resulting in a decrease in holding power. However, if the gel fraction is too high, the cohesive strength tends to increase, resulting in a decrease in adhesive strength.

[0142] The gel fraction is an index of the degree of crosslinking and is calculated, for example, by the following method. That is, a pressure-sensitive adhesive sheet (without a release sheet) consisting of a substrate polymer sheet (e.g., a PET film) on which a pressure-sensitive adhesive layer is formed is wrapped in a 200-mesh SUS wire netting and immersed in toluene at 23°C for 24 hours, and the gel fraction is calculated as the weight percentage of the insoluble pressure-sensitive adhesive component remaining in the wire netting after immersion relative to the weight of the pressure-sensitive adhesive component before immersion, excluding the weight of the substrate.

[0143] Furthermore, such a PSA sheet may be protected by providing a release sheet on the outer side of the PSA layer, if necessary. In a PSA sheet in which the PSA layer is formed on one side of a substrate, the PSA layer can be protected by applying a release treatment to the side of the substrate opposite the PSA layer, thereby utilizing the release-treated surface.

[0144] The pressure-sensitive adhesive of the present invention can be used to bond various components, and in particular, it is used as a single-sided or double-sided pressure-sensitive adhesive sheet used to bond optical components, and as a single-sided or double-sided pressure-sensitive adhesive sheet for fixing components of portable electronic devices and electronic components. [Example]

[0145] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. In the examples, "parts" and "%" are by weight.

[0146] In the examples below, the number average molecular weight, weight average molecular weight, biomass degree, recycled carbon usage rate, glass transition temperature, hydroxyl value, acid value, and gel fraction of the adhesive layer of the polyester resin, as well as the biomass degree and recycled carbon usage rate of the polyester resin composition were measured according to the methods described above.

[0147] The polyester resins were produced by the following method (see Table 1).

[0148] [Examples 1 to 4, Comparative Examples 1 and 2] [Production of Polyester Resins (A) [A-1 to A-5] and (A') [A'-1 to A'-2]] In a reactor equipped with a thermometer, a stirrer, a distillation column, a nitrogen inlet tube, and a vacuum device, polycarboxylic acids and polyols were blended as shown in Table 1, and tetrabutyl titanate was added as a catalyst at 0.2 mmol / mol relative to the polycarboxylic acids. The internal temperature was gradually raised to 240-250°C, and an esterification reaction was carried out over 4 hours. The internal temperature was then raised to 260°C, and tetrabutyl titanate was added as a catalyst at 0.2 mmol / mol relative to the polycarboxylic acids. The pressure was reduced to 1.33-2.66 hPa, and a polymerization reaction was carried out over 2-3 hours to produce polyester resin (A) or (A'). The composition ratio and physical properties of the resulting polyester resin (A) or (A') are shown in Table 2 below. The plant-derived raw materials used in the above production were hydrodistilled dimer acid, sebacic acid, and 1,3-propane glycol. Furthermore, some of the terephthalic acid and ethylene glycol were derived from PET.

[0149] Comparative Example 3 [Production of Polyester Resin (A') [A'-3]] In a reactor equipped with a thermometer, a stirrer, a distillation column, a nitrogen inlet tube, and a vacuum device, polycarboxylic acids and polyols were blended as shown in Table 1, and tetrabutyl titanate was added as a catalyst at 0.2 mmol / mol relative to the polycarboxylic acids. The internal temperature was gradually raised to 220°C, and an esterification reaction was carried out over 4 hours. Thereafter, at an internal temperature of 220°C, tetrabutyl titanate was added as a catalyst at 0.2 mmol / mol relative to the polycarboxylic acids, the pressure was reduced to 600 to 700 hPa, and a polymerization reaction was carried out over 4 hours to produce polyester resin (A'-3). The composition ratio and physical properties of the obtained polyester resin (A') are shown in the following Table 2. The hydroxyl value and acid value in Table 2 were measured in accordance with JIS K0070. In the above production, the plant-derived raw material was hydrodistilled dimer acid, and part of the terephthalic acid and ethylene glycol were derived from PET.

[0150] [Table 1]

[0151] [Table 2]

[0152] Next, prior to preparing a polyester resin composition (adhesive composition), the following components were prepared.

[0153] [Polyisocyanate compound (B)] Polyisocyanate compound (B-1): "Coronate L55E, solids concentration 55%" (manufactured by Tosoh Corporation)

[0154] [Hydrolysis inhibitor (C)] Carbodiimide compound (C-1): "Carbodilite V-09GB, solid content 70%" (Nisshinbo Chemical Co., Ltd.)

[0155] Using the above polyester resin, crosslinking agent, and hydrolysis inhibitor, polyester resin compositions (adhesive compositions) were prepared as follows according to the formulations shown in Tables 3 and 4 below, and adhesive sheets were produced.

[0156] [Examples 1-1 to 5-2, Comparative Examples 1-1 to 3-2] The polyester resin (A) or (A') obtained above was diluted with ethyl acetate to a solids concentration of 50%, and a polyisocyanate compound (B-1) and a carbodiimide compound (C-1) were blended in the blending ratios (solids content ratios) shown in Tables 3 and 4. 0.02 parts (solids content) of a zirconium compound ("Orgatics ZC-150" manufactured by Matsumoto Fine Chemical Co., Ltd.) diluted with acetylacetone to a solids concentration of 1% was added as a urethane catalyst, and the mixture was stirred and mixed to obtain a polyester resin composition (adhesive composition). The obtained pressure-sensitive adhesive composition was applied to a polyethylene terephthalate (PET) film (thickness: 38 μm) so that the thickness after drying would be approximately 25 μm, and then dried for 3 minutes at 100° C. to form a pressure-sensitive adhesive layer. A release-treated PET film (release film) was then attached to the pressure-sensitive adhesive layer to protect its surface, and the layer was aged for 10 days in an atmosphere at a temperature of 40° C. to obtain a pressure-sensitive adhesive sheet.

[0157] The resulting pressure-sensitive adhesive sheets of the Examples and Comparative Examples were evaluated as follows, and the evaluation results are shown in Tables 3 and 4 below.

[0158] <Initial adhesive strength (peel strength) (to SUS)> A SUS-BA plate was prepared as the adherend. The pressure-sensitive adhesive sheet obtained above was cut to 25 mm x 200 mm in an environment of 23 °C and 50% RH, after which the release film was peeled off, and the pressure-sensitive adhesive layer side was placed against the SUS-BA plate, and a 2 kg roller was pressed back and forth to adhere the sheet. After leaving the sheet to stand for 30 minutes in the same atmosphere, the 180-degree peel strength (N / 25 mm) was measured at a peel rate of 300 mm / min using an autograph (Shimadzu Corporation, Autograph AGS-H 500N), and the peeling state was visually observed.

[0159] <Adhesion strength (peel strength) after 72 hours (to SUS)> A SUS-BA plate was prepared as the adherend. The pressure-sensitive adhesive sheet obtained above was cut to 25 mm x 200 mm in an environment of 23°C and 50% RH, after which the release film was peeled off, and the pressure-sensitive adhesive layer side was placed against the SUS-BA plate, and a 2 kg roller was pressed back and forth to adhere the sheet. After leaving the sheet in the same atmosphere for 72 hours, the 180° peel strength (N / 25 mm) was measured at a peel rate of 300 mm / min using an autograph (Shimadzu Corporation, Autograph AGS-H 500N), and the peeling state was visually observed. Evaluation was also performed according to the following criteria. (Evaluation criteria) ◎ The peel strength was 20N / 25mm or more and interfacial peeling occurred. ○ Peel strength was 20N / 25mm or more and cohesive failure occurred. ○ Peel strength was 15N / 25mm or more and less than 20N / 25mm, and interfacial peeling occurred. △: The peel strength was 15N / 25mm or more and less than 20N / 25mm, and cohesive failure occurred. × Peel strength is less than 15N / 25mm (regardless of peeling condition).

[0160] <Initial adhesive strength (peel strength) (vs. PP)> A PP plate was prepared as the adherend. The pressure-sensitive adhesive sheet obtained above was cut into 25 mm x 200 mm pieces under an environment of 23°C and 50% RH, after which the release film was peeled off, and the pressure-sensitive adhesive layer side was placed against the PP plate, and a 2 kg roller was used to pressurize and adhere the sheet. After leaving the sheet for 30 minutes under the same atmosphere, the 180° peel strength (N / 25 mm) was measured at a peel rate of 300 mm / min using an autograph (Shimadzu Corporation, Autograph AGS-H 500N), and the peeling state was visually observed. Evaluation was also performed according to the following criteria. (Evaluation criteria) ○ Peel strength was 10N / 25mm or more and interfacial peeling occurred. △: The peel strength was 10 N / 25 mm or more and cohesive failure occurred. △: The peel strength was 5N / 25mm or more and less than 10N / 25mm, and interfacial peeling occurred. × The peel strength was 5 N / 25 mm or more and less than 10 N / 25 mm, and cohesive failure occurred. × Peel strength is less than 5N / 25mm (regardless of peeling condition).

[0161] <Holding force (cohesive force)> The pressure-sensitive adhesive sheet obtained above was applied to a SUS304 substrate in accordance with JIS Z-0237, with an area of ​​25 mm x 25 mm, and then left to stand at 80°C for 20 minutes. A load of 1 kg was then applied and the time until the sheet fell off was measured, or for sheets that had not fallen off after 24 hours of standing, the displacement after 24 hours was measured and evaluated according to the following criteria. (Evaluation criteria) ◎ After leaving it for 24 hours, it did not fall off and the displacement was within 1 mm. ○: It did not fall off even after being left standing for 24 hours, but the displacement exceeded 1 mm. ×: The sample fell off after being left standing for 24 hours.

[0162] [Table 3]

[0163] [Table 4]

[0164] The results in Table 3 above show that the adhesive sheets of Examples 1-1 to 5-2, which were made from adhesive compositions containing the polyester resin compositions of Examples 1 to 5 in Table 2, had excellent initial and post-aging adhesion to metal substrates, and further had the desired adhesion even to difficult-to-adhere substrates such as polyolefin resins, and had an excellent balance of adhesive strength and holding power. Furthermore, the results of Table 4 above show that the adhesive sheets of Comparative Examples 1-1 to 1-3, which were made from adhesive compositions containing the polyester resin composition of Comparative Example 1 in Table 2, which did not contain an aromatic dicarboxylic acid as a copolymerization component of polycarboxylic acids and contained only dimer acid, had particularly low adhesive strength over time. Furthermore, the adhesive sheets of Comparative Examples 2-1 to 2-2, which were made from adhesive compositions containing the polyester resin composition of Comparative Example 2 in Table 2, which did not contain aromatic dicarboxylic acid but contained aliphatic dicarboxylic acid and dimer acid, had a poor balance between strong adhesive strength and holding power. Furthermore, the adhesive sheets of Comparative Examples 3-1 to 3-2, which were made from adhesive compositions containing the polyester resin composition of Comparative Example 3 in Table 2, which has a number average molecular weight of less than 3000, showed poor results in both adhesive strength and holding power, and did not satisfy all of the effects of the present invention. [Industrial Applicability]

[0165] The polyester-based resin composition of the present invention, the pressure-sensitive adhesive composition containing the same, and the pressure-sensitive adhesive have excellent adhesive properties for various adherends such as metals and plastics, even when a polyester-based resin with a high bioplasticity and recycled carbon usage rate is used, and are used as single-sided or double-sided pressure-sensitive adhesive sheets for bonding optical components, single-sided or double-sided pressure-sensitive adhesive sheets for fixing components of portable electronic devices, and single-sided or double-sided pressure-sensitive adhesive sheets for fixing electronic components, etc.

Claims

1. A resin composition containing a polyester-based resin (A), the polyester resin (A) contains a structural unit derived from at least one compound (a1) selected from dimer acid and dimer diol, and a structural unit derived from an aromatic compound (a2); The biomass degree of the polyester resin (A) is 70% or more, The number average molecular weight of the polyester resin (A) is 3,000 or more, When the compound (a1) is a dimer acid, the content of the dimer acid is 20 to 90 mol % based on the total amount of the polycarboxylic acids; When the compound (a1) is a dimer diol, the content of the dimer diol is 20 to 90 mol% based on the total polyol, When the aromatic compound (a2) is an aromatic polycarboxylic acid, the content of the aromatic polycarboxylic acid is 5 to 47 mol% based on the total amount of the polycarboxylic acids, When the aromatic compound (a2) is an aromatic polyol, the content of the aromatic polyol is 5 to 40 mol % based on the total polyol content.

2. The polyester resin composition according to claim 1, characterized in that the polyester resin (A) further contains structural units derived from an aliphatic polyol, and 10 mol % or more of the structural units derived from the aliphatic polyol are structural units derived from an acyclic aliphatic diol having 2 to 20 carbon atoms.

3. 3. The polyester resin composition according to claim 1, wherein the weight average molecular weight of the polyester resin (A) is 10,000 or more.

4. The polyester resin composition according to any one of claims 1 to 3, further comprising a polyisocyanate compound (B).

5. The polyester resin composition according to any one of claims 1 to 4, further comprising a hydrolysis inhibitor (C).

6. A pressure-sensitive adhesive composition comprising the polyester resin composition according to any one of claims 1 to 5.

7. A pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition according to claim 6.

8. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive according to claim 7.

9. A double-sided pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive according to claim 7.